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1、链接：recover-binary-search-tree 来源：牛客网Two elements of a binary search tree (BST) are swapped by mistake.Recover the tree without changing its structure.Note: A solution using O(n ) space is pretty

1、链接：minimum-depth-of-binary-tree 来源：牛客网Given a binary tree, find its minimum depth.The minimum depth is the number of nodes along the shortest path from the root node down to the nearest leaf node.2、思

1、链接：linked-list-cycle 来源：牛客网 Given a linked list, determine if it has a cycle in it. Follow up: Can you solve it without using extra space?2、思路：设置快慢指针，如果有cycle则会相遇，没有的话，快指针最终会走到tail 3、代码：public cl

1、题目：sum-root-to-leaf-numbers 来源：牛客网 Given a binary tree containing digits from0-9only, each root-to-leaf path could represent a number.An example is the root-to-leaf path1->2->3which represents the n

1、populating-next-right-pointers-in-each-node-ii 来源：牛客网Follow up for problem "Populating Next Right Pointers in Each Node".What if the given tree could be any binary tree? Would your previous solution

1、链接：path-sum 来源：牛客网热度指数：5068时间限制：1秒空间限制：32768KGiven a binary tree and a sum, determine if the tree has a root-to-leaf path such that adding up all the values along the path equals the given sum.For

1、来源：unique-paths-iiFollow up for “Unique Paths”: Now consider if some obstacles are added to the grids. How many unique paths would there be? An obstacle and empty space is marked as1and0respectivel

1、来源：minimum-path-sumGiven a m x n grid filled with non-negative numbers, find a path from top left to bottom right which minimizes the sum of all numbers along its path. Note: You can only move eithe

1、来源：longest-common-prefix Write a function to find the longest common prefix string amongst an array of strings.2、思路在代码中写明了，直接看代码：package leetcode;import java.util.Arrays;/** * 对字符串排序，假如几个字符串前缀相同，那

1、题目： 链接：permutations Given a collection of numbers, return all possible permutations. For example, [1,2,3]have the following permutations: [1,2,3],[1,3,2],[2,1,3],[2,3,1],[3,1,2], and[3,2,1].2、思路

1、链接：这里写链接内容 A robot is located at the top-left corner of a m x n grid (marked 'Start' in the diagram below).The robot can only move either down or right at any point in time. The robot is trying to r

1、来源：two-sumGiven an array of integers, find two numbers such that they add up to a specific target number. The function twoSum should return indices of the two numbers such that they add up to the ta

1、链接：symmetric-tree来源：牛客网Given a binary tree, check whether it is a mirror of itself (ie, symmetric around its center).For example, this binary tree is symmetric: 1 / \ 2 2 / \ / \3 4 4

1、unique-binary-search-trees 来源：牛客网Given n, how many structurally unique BST's (binary search trees) that store values 1...n?For example,Given n = 3, there are a total of 5 unique BST's. 1

1、链接：path-sum-ii 来源：牛客网Given a binary tree and a sum, find all root-to-leaf paths where each path's sum equals the given sum.For example:Given the below binary tree andsum = 22, 5

1、链接：balanced-binary-tree来源：牛客网Given a binary tree, determine if it is height-balanced. For this problem, a height-balanced binary tree is defined as a binary tree in which the depth of the two subtre

1、来源：rotate-listGiven a list, rotate the list to the right by k places, where k is non-negative. For example: Given1->2->3->4->5->NULLand k =2, return4->5->1->2->3->NULL.2、思路，递归的本质是栈，例子中进栈1、2、3、4、5，

1、来源：sort-colorsGiven an array with n objects colored red, white or blue, sort them so that objects of the same color are adjacent, with the colors in the order red, white and blue.Here, we will use t

1、来源：climbing-stairs 来源：牛客网You are climbing a stair case. It takes n steps to reach to the top.Each time you can either climb 1 or 2 steps. In how many distinct ways can you climb to the top?2、思路：直接

1、来源：partition-list 牛客网Given a linked list and a value x, partition it such that all nodes less than x come before nodes greater than or equal to x.You should preserve the original relative order of t

1、来源：merge-sorted-array 牛客网Given two sorted integer arrays A and B, merge B into A as one sorted array.Note: You may assume that A has enough space to hold additional elements from B. The number of

1、来源：binary-tree-zigzag-level-order-traversal牛客网Given a binary tree, return the zigzag level order traversal of its nodes' values. (ie, from left to right, then right to left for the next level and alt

1、来源：construct-binary-tree-from-preorder-and-inorder-traversal Given preorder and inorder traversal of a tree, construct the binary tree. Note: You may assume that duplicates do not exist in the tr

1、链接：path-sum 来源：牛客网Given a binary tree and a sum, determine if the tree has a root-to-leaf path such that adding up all the values along the path equals the given sum.For example:Given the below bi

1、来源：sum-root-to-leaf-numbers 来源：牛客网Given a binary tree containing digits from0-9only, each root-to-leaf path could represent a number.An example is the root-to-leaf path1->2->3which represents the n

1、链接：这里写链接内容来源：牛客网Given inorder and postorder traversal of a tree, construct the binary tree. Note: You may assume that duplicates do not exist in the tree.2、思路，通过中序和后序来构建树：前序的第一个元素为当前根结点root；在后序中

1、word-break Given a string s and a dictionary of words dict, determine if s can be segmented into a space-separated sequence of one or more dictionary words. For example, given s =”leetcode”, dict

1、链接：convert-sorted-list-to-binary-search-tree 来源：牛客网Given a singly linked list where elements are sorted in ascending order, convert it to a height balanced BST.2、思路：通过快慢指针找到中间结点，将中间结点设置为空（注意设置该结点为空，需

1、留坑吧。。。看不懂别人的代码

1、题目链接：点击打开链接2、题目：Given an array of n integers where n > 1, nums, return an array output such that output[i] is equal to the product of all the elements ofnums except nums[i].Solve it wi

1、来源：点击打开链接2、题目：Given two strings s and t which consist of only lowercase letters.String t is generated by random shuffling string s and then add one more letter at a random position.F

1、来源：点击打开链接2、There are n bulbs that are initially off. You first turn on all the bulbs. Then, you turn off every second bulb. On the third round, you toggle every third bulb (turning on if it'

1、来源：点击打开链接2、题目：Given an array nums, write a function to move all 0's to the end of it while maintaining the relative order of the non-zero elements.For example, given nums = [0, 1, 0, 3

1、来源：点击打开链接2、题目：You are playing the following Nim Game with your friend: There is a heap of stones on the table, each time one of you take turns to remove 1 to 3 stones. The one who removes th

1、题目：点击打开链接2、题目：Given a binary tree, return the inorder traversal of its nodes' values.For example:Given binary tree [1,null,2,3], 1 \ 2 / 3return [1,3,2].

1、来源：点击打开链接2、内容：Given a non-negative integer num, repeatedly add all its digits until the result has only one digit.For example:Given num = 38, the process is like: 3 + 8 = 11, 1 +

1、来源：144. Binary Tree Preorder Traversal2、题目：Given a binary tree, return the preorder traversal of its nodes' values.For example:Given binary tree {1,#,2,3}, 1 \ 2 /

1、来源：点击打开链接2、题目：Calculate the sum of two integers a and b, but you are not allowed to use the operator + and -.Example:Given a = 1 and b = 2, return 3.3、代码（主要还是参考了这里点击打开链接）：class S

1、题目来源：100. Same Tree2、题目：Given two binary trees, write a function to check if they are equal or not.Two binary trees are considered equal if they are structurally identical and the nodes

来源：104. Maximum Depth of Binary Tree题目要求：Given a binary tree, find its maximum depth.The maximum depth is the number of nodes along the longest path from the root node down to the fart